(1) Field of the Invention
The present invention relates to a semiconductive rubber foam. More particularly, the present invention relates to a semiconductive rubber foam composed of a chlorinated ethylene/.alpha.-olefin copolymer having a volume resistivity of 10.sup.5 to 10.sup.11 .OMEGA.-cm as the foam, which is excellent in heat aging resistance and ozone resistance and retains the initial softness even after the lapse of time without breaking by ozone deterioration.
(2) Description of the Related Art
The electrophotographic printing process is generally adopted for a copying machine, a laser printer and the like. Since electric charging is utilized for the mechanism in these machines, electric characteristics are often limited even in a delivery roll.
A chloroprene rubber has heretofore been used for such rolls.
However, a chloroprene foamed body is defective in that thermal deterioration is caused at a used atmospheric temperature or deterioration is caused by ozone present in a used atmosphere, and the foamed body becomes rigid with the lapse of time and paper-feeding performances are degraded.
Accordingly, use of a foamed rubber roll prepared by using an ethylene/propylene rubber EPDM has been tried. However, in this case, it is difficult to control the volume resistivity though the initial softness can be retained even after the lapse of time, and it has been found that this foamed rubber roll, therefore, cannot be put into practical use.